In recent years, a more flexible system configuration became possible by a plurality of virtual machines operating on one physical server. In such a system, a system load distribution, a failure avoidance and so on can be realized by a migration technique in which an operating virtual machine is migrated to another physical server and a memory area without stopping the operating virtual machine.
As a technique of the migration, for example, WO 2005/083569 (Patent Literature 1), JP 2009-146106A (Patent Literature 2), JP 2004-78465A (Patent Literature 3) are known.
Patent Literature 1 discloses a network system which is provided with a switching controller of an operating server and a connection controller which switches a connection destination to a switching destination target network which contains a backup server from a target network which contains a main server. In such a configuration, a system disclosed in Patent Literature 1 is possible to carry out a process migration without the service stop to a user and the re-setting of a communication.
Patent Literature 2 discloses a storage system in which an access route to an identical storage is changed by switching a physical port as an addition destination of a virtual port to another physical port and updating a routing table of a switch unit based on identification data of a physical port of a switching destination.
Patent Literature 3 discloses a technique in which a run-down time of a migration object process in process migration processing is reduced.
In a computer system in which a plurality of computers are connected through a network, generally, a network manager who manages the network and an IT (information technology) manager who manages the computers are required individually. The IT manager carries out the migration of a virtual machine in consideration of a load on the side of the computer (for example, a usage rate of a CPU and a memory) but in no consideration of the load on the side of the network. When migrating a memory image of the virtual machine, there is a case that the transmission of data is carried out through the network. During this period, access to the virtual machine continues in no consideration of the migration of the memory image on the side of the network. Therefore, there is a fear that the traffic which occurs with the migration of the virtual machine obstructs communication with a migration object virtual machine and another virtual machine.